I personally think CHE's are little better than fire hazards. But lots of people find that they work very well.
I'm a big fan of Radiant Heat Panels and have several.
There are two to look for. Reptile Basics makes a very good panel, you can google them. Also Pro-Products (https://pro-products.com/) makes top quality stuff. You need to call and order over the phone but the gentleman, Bob, is really thorough. He'll ask a list of questions so that he can sell you exactly what you need for your set up.
I've never used one in a glass tank, only in PVC enclosures, so I'm not sure how well an RHP would preform, but I suspect it would be fine and really easy to attach to the top.